How to build alliance with neutral tribes in American Conquest?
The first random map I played it worked. Now I play another one, and I just cannot... I keep attacking them, but they are not offering me the opportunity to form an alliance and start training troops trough them...
Help me out here please. Thanks

Create a priest / shaman (depending on your nation) and send it to the neutral tribe. You will be promted a message like "Do you want to trade?", it does consume the priest/shaman.

Any officer will do too.